Tuning indicator system



June 7, 1949. Q c, ElL, JR" ETAL 2,472,536

TUNING INDICATOR SYSTEM Fild Nov. 25, 1947 .smnon .seLecroR \45 clRcu/rsPatented June 7, 1949 TUNING INDICATOR SYSTEM Otto C. Keil, Jr.,Quakertown, and Jesse Hewitt Lofto'n, Havertown, Pa., assig'nors toPhilco Corporation, Philadelphia, Pa., a corporation of PennsylvaniaApplication November 25, 1947, Serial No. 788,052

The invention herein described and claimed relates to an improved.annunciator system adapted for use in selective multi-circuitcommunication and signaling apparatus. More particularly, the inventionrelates to an improved visual-indicator system employing individualindicating means, preferably lamps, for identifying the circuit orstation selected.

The present invention may be eniployed .to excellent advantage inpushbutton-operated radio receivers, particularly radio receivers whichuse a non-latching type of pushbutton mechanism, either for station orwave-band selection. Non-latching pushbutton mechanisms have been foundto be particularly useful in automobile radio receivers where it isdesired to provide tuning means controlled both by hand-operatedpushbutton station-selector mechanism and by a foot-operatedstation-selector switch.

It will be understood that in a non-latching type of selector mechanism,a pushbutton, when depressed, returns to released position as soon asthe pressure of the operators finger is removed; and thereafter, allpushbuttons occupy similar released positions. It is hence impossible toascertain, from merely looking at the pushbuttons, the station to whichthe receiver is tuned, and it is necessary to provide some means ofidentifying the station. That is the function of the annunciation orvisual-indicator system whose improved circuit arrangement is thesubject matter of the present invention.

The invention may be used to excellent advantage in radio receiversemploying the non-latching type of pushbutton mechanism described andclaimed in the copending application of Gilbert J, Kennedy, Serial No.754,013, filed June 11, 1947, and assigned to the assignee of thepresent invention.

It is an object then of this'invention to provide an improvedannunciator or visual-indicator system for selective multi-circuitcommunication and signaling apparatus.

It is another object of this invention to provide an improved indicatinglamp system for use in pushbutton-operated radio receivers.

It is a more specific object of this invention to provide, in a radioreceiver having a non-latching type of pushbutton selector mechanism,improved means for identifying, by the lighting of an individualindicator lamp, the station and/or wave band to which the receiver istuned.

In a preferred embodiment of the presentinvention employed in a radioreceiver having nonlatching pushbutton station selectors, when a 4Claims. (Cl. 177-353) selected pushbutton is depressed by the operator,all indicator lamps are immediately extinguished and all remain inextinguished condition until a rotary switch, through whose agency thestation selection is accomplished, has completed its'stepby-steprotation, at which time the individual indicator lamp, associated withthe selected station, is automatically illuminated. The undesirableflashing of lamps, which would otherwise occur as the rotary switchpassed through various station positions during the course of itsrotation, is eliminated by the means of the present invention.

These and other objects, features and advantages of the presentinvention, and the manner in which the objects are attained, will becomeclear from a consideration of the following description and of theaccompanying drawing, wherein:

Figure 1.is a schematic representation of visual indicator meansembodying a preferred form of the present invention; and f Figures 2, 3,and 4 are schematic representations which will be helpful in describingand understanding the operation of the circuit of Figure 1.

Referring now 'to Figure .1, there is shown a portion of a radioreceiver including six stationselector'pushbuttons l li6, individualindicator lamps "-22 associated with the six pushbuttons, a rotaryswitch 23, a source of direct-current voltage 29, and conductors 31-42and 3'la- 42a for effecting various circuit connections to be described.

In Figure 1, rotary switch 23 is comprised of a solenoid 24, acombination switch and pawl 25, a ratchet 26, a wafer-section 21, and awafersection 28. The switch contacts of switch-pawl 25 are normallyclosed, as shown in the drawing, but when solenoid 24 is actuated, aswill be described, the movable switch-arm 25a is ,pulled' .Wafer-section21 oi rotary switch 23 includes a plurality of wiper contacts H and adisc-like rotor 3| having recessed portions or notches 32 and 33, spaced180 apart. Wafer-section 28 includes a plurality of wiper-contacts h-nand a disc-like rotor 34 having extending portions or contacts 35 and 36which are in radial alignment with notches 32 and 33 of rotor 3|.

Ratchet 26, rotor 3|, and rotor 34 are splined or keyed to a commonshaft 30, as is indicated in Figure 1 by the dotted-line representation49, and when ratchet 28 is rotatably moved, rotors 3| and 34 rotate incorresponding manner.

In Figure l, wiper-contacts a-f terminate conductors 3142 from lamps"-22 at rotor 3|; and wiper-contact a terminates conductor 44 fromswitch 25. Wiper-contacts h-m terminate conductors 310-4211 from lamps|1-22 at rotor 34; and wiper-contact n terminates ground connection 46.

In the particular arrangement illustrated in Figure 1, there are threeequally-spaced wipercontacts per switch quadrant. Therefore, ,the switchmechanism, comprising solenoid 24, pawlarm a and ratchet 26, is soconstructed as to move rotors 3| and 34 through sectors for eachactuation of the rotary switch.

A plurality of pre-tuned station-selector circuits, indicated generallyin Figure 1 by block 48, are operatively associated with rotary switch23. being mechanically connected to shaft 30 by known means, indicatedby the dotted-line representation 43. Upon each actuation of thesolenoid, the station selector device 48 is switched from one position,in which a predetermined station is received, to another position, inwhich a diflerent station is received. Such pre-tuned station-selectingcircuits are well known in the art and it is unnecessary to describedevice 48 in greater detail.

4 divides substantially equally among the other indicator lamps |822,these five lamps being in parallel with each other, as just described.Each of these five lamps therefore receives but onefifth of the totalcurrent.

In accordance with the present invention, the circuit constants are sochosen that, while the total current in the above or similar circuit,when passed through a series-connected indicator lamp, is adequate toeffect illumination, i. e., incandescence, thereof, one-fifth of thetotal current is not sufficient to eflect illumination. In addition, thecircuit constants are so chosen that the total current through theabove-described or similar circuit, while sufiicient to illuminate anindicator lamp, is insufilcient to actuate solenoid 24. Hence, in theexample being described, with all pushbuttons in released positions,indicator lamp |1 remains illuminated as a result of a prior actuationof pushbutton all other lamps remain extinguished, and the receiverremains tuned to the station associated with pushbutton H and identifiedby lamp l1.

Assume now that the operator presses, say pushbutton l4, with theintention of tuning in the station associated therewith. As soon aspushbutton I4 is depressed, lamp I1 is extin- The operation of thecircuit of Figure 1 will now be described. It is believed that anunderstanding of the invention will be facilitated by describing, insequence, a series of assumed operating conditions.

Assume first that, as the description starts, the receiver is inoperation and that, as a result of pushbutton having been previouslydepressed by the operator, the receiver is tuned to the stationassociated therewith. All pushbuttons are now in released position,since, as described above, the pushbutton mechanism is of thenon-latching type and a button remains depressed only so long as thefinger of the operator is in engagement therewith.

Indicator lamp l1, associated with pushbutton II, is illuminated, butall other indicator lamps are extinguished. The circuit components andconnections which effect this condition may be reduced to the circuitshown schematically in Figure 2. By referring to Figures 1 and 2 it willbe observed that a circuit is completed from the grounded terminal ofvoltage source 29 through lamp H to ground by way of the following'circuit components: voltage source 23, solenoid 24, the normally closedswitch-contacts of switch 25, conductor 44, wiper-contact a, rotor 3|,wipercontacts b-f, conductors 38-42 in parallel, lamps |822 in parallel,conductor 43, lamp l1, conductor 31, conductor 31a, wiper-contact h,contact 35, rotor 34, wiper-contact n, and ground connection 46. Observethat the current, which passes, by way of the above-described circuit,

through lamp to effect illumination thereof,

guished, tor the current, which previously passed through theseries-connected lamp l1 and through the bank of parallel-connectedlamps |822, is now passed directly to ground 41, by way of the closedcontacts of depressed pushbutton |4. The circuit which exists at theinstant pushbutton I4 is depressed is shown in reduced form in Figure 3and comprises the following: voltage source 29, solenoid 24, the closedcontacts of switch 25, conductor 44, wiper-contact g, rotor 3|, and,forming a low resistance bypass across the entire indicating-lampcircuit, wiper-contact d, conductor 40, the closed contacts ofpushbutton I4, and the ground connection 41. When the indicator lampsare thus bypassed, the resistance of thebattery-throughsolenoid-to-ground circuit is decreased, the magnitude ofthe current through solenoid 24 is increased, and the increased currentis adequate to actuate the solenoid;

When solenoid 24 is thus actuated, the movable pawl-arm 25a is drawnupwardly, i. e., toward the solenoid, and ratchet 26 is moved rotatablyin a clockwise direction. When pawlarm 25a moves upwardly, the contactsof switch 25 open, but it will be understood that the establishedmagnetic field of solenoid 24 is effective to complete the upward strokeof the pawl-ann, thus moving ratchet 26 through 30 of rotation.

When solenoid 24 is actuated and ratchet 26 is rotated, by pawl-arm 25a,as just described, rotors 3| and 34, being splined to common shaft 30,move rotatably clockwise, as is indicated by the arrows in Figure 1.Connection is made substantially immediately between rotor 3| andwiper-contact a, and, concurrently connection is broken at contact 35between rotor 34 and wipercontact h. Pawl-arm 25a completes its stroke,as above described, and rotors 3| and 34 move through 30 of rotation,thus bringing notch 22 and contact 35 to the positions occupied bywiper-contactsb' and 2', respectively. At or about this time, pawl-arm25a is released by solenoid 24 and returns to the de-energized position,thereby again closing the switch contacts of switch 25. Lamp I8 is nowconnected in a manner similar to that of lamp II in Figure 3, i. e.,lamp I8 now occupies the position between the bank of cuit now obtainingmay be traced in Figure 1 as follows: voltage source 23, solenoid 24,the againclosed contacts of switch 25, conductor 44, wipercontact 9,rotor 3|, wiper-contacts a, c-f, conductors 31, 39-42 in parallel, lampsI1, "-22 in parallel, conductor 43, lamp I8, conductors 33,

38a, wiper-contact 1, contact 35, rotor 34 and ground connection 46.When so connected. lamp l8 does not become illuminated, for, aspreviously described with respect to lamp ll, the lamp circuit bypassedby the low-resistance path which extends from rotor 3| to ground 41 byway of the closed contacts of the depressed pushbutton, i. e.,pushbutton M. The current through solenoid 24 therefore remainssubstantially the same as that which obtained when pushbutton l4 wasfirst depressed. Solenoid 24 therefore remains energized, pawl-arm 25ais again drawn upwardly, ratchet 26 is again moved through 30 ofrotation, and rotors 3| and 34 are moved in like manner.

The action described above continues, in well known step-by-stepfashion, until the low-resistance path, through solenoid 24 to ground41, by way of the still-closed contacts of pushbutton I4, is broken atrotor 3| by the arrival of notch 32 at the position occupied bywiper-contact d associated with conductor 40 and depressed pushbuttonl4.

After the connection between rotor 3| and conductor 40 is broken atwiper-contact d, as above described, a path obtains-from voltage source25 through solenoid 24 to ground which may be traced as follows: battery29, solenoid 24, the again-closed contacts of switch 25, conductor 44,wiper-contact g, rotor 3|, wiper-contacts aF-c, e, f, conductors 31-39,4|, 42 in parallel, lamps 9, 2|, 22 in parallel, conductor 43, lamp 20,and then, assuming pushbutton H to be still depressed, to ground by wayof parallel paths, one comprising the closed contacts of pushbutton I4and ground connection 41, and the otherpath comprising conductor 40a,wiper-contact k, contact 35, rotor 34 and ground connection 45. The

reduced circuit is shown schematically in Figure 4.

It will be observed that in the circuit of Figure 4, just described,lamp 20 is in series with a parallel network comprised of the remainingfive lamps and associated conductors. It is apparent that the resistanceof the circuit of Figure 4 is increased over that of the'circuit ofFigure 3, for in Figure 4 the bank of parallel-connected lamps and thesingle series-connected lamp 20 are in series with solenoid 24 whereasin Figure 3 the lamps are shunted by a path of negligible resistance.The current through solenoid 24 is hence decreased with respect to thatwhich obtained in the circuit of Figure 3; and this decreasedpurrent isinsuflicient to actuate solenoid 24.

It will be seen from the above that the step-bystep action of rotaryswitch 23 ceases when the low-resistance shunt path through the closedcontacts of the depressed push-button is broken by the arrival of notch32 at. the wiper-contact associated with the depressed pushbutton. Thecurrent in the circuit then obtaining, i. e. the current in the circuitshown in Figure 4, while insuflicient to actuate solenoid 24, is, aspreviously described, adequate to illuminate the seriesconnected lamp 20associated with the depressed pushbutton l4. However, each of the otherlamps,

- being in shunt with each other, draws but one fifth o! the totalcurrent, which is to eii'ect incandescence. I

The receiver has now been tuned, through the agency of the pre-tunedstation-selector circuits. to the station identified with pushbutton l4:and the operator is informed that this has been accomplished by thelighting of lamp 20. In practice, the action is fast, and the selectedstation is obtained without appreciable delay. The operator thereuponreleases the depressed pushbutton, 1. e., pushbutton 20 in the presentexample, and the circuit of Figure 4 becomes similar to that shown inFigure 2, with the exception of course that lamp 2o occupies theposition occupied in Figure 2 by lamp II.

In prior art circuits of which we have'know ledge, indicator lampsassociated with non-depressed pushbuttons are illuminated as thevarinsumcient ions wipe-contacts are passed during the homing action ofthe rotary switch. And, since the pushbuttons and indicator lamps areordinarily in ,sequential arrangement, the illumination will appear torun along the dial. This is an undesirable condition which is completelyeliminated by the improved circuit of the present invention. For, asdescribed above, all indicator lamps are extinguished as soon as apushbutton is depressed, that is, as soon as a pushbutton is depressedto tune in a station other than the station to which the receiver isalready tuned. Thereafter, no indicator lamps become illuminated untilthe homing action of the rotary switch is completed, at which time theindividual indicator lamp identified with the selected station islighted.

Attention is invited to the fact that the visualindicator system of thepresent invention will correctly identify the station received, eventhough the station received is not identified with the particularpushbutton depressed. For, in a radio receiver equipped withstation-selector mechanism actuated by a rotary switch, it is quitepossible, ordinarily, for the operator to tune in a station other thanthe station identified with a the particular depressed pushbutton. Forexample, assume again that in Figure 1 the receiver is tuned to thestation associated with pushbutton H and that the operator pressespushbutton Assume further, however, that the operator releasespushbutton l4 after the rotary switch has moved through but two steps,i. e., through 60 instead of 90". In such case, the station associatedwith pushbutton l3 will be received instead of the station associatedvwith pushbutton |4. Observe, however, that the visual indicating systemof the present invention will correctly identify the station received.For, under the circumstances just assumed, lamp I! will becomeilluminated rather than lamp 2|. This will be readily. apparent fromFigure 1 and from the circuit descriptions previously given. Theindicating system of the present invention is readily adapted to use inautomobile radio receivers which employ a foot-operated switch as anauxiliary to the hand-operated pushbutton mechanism. In Figure l, theconnection 5| and the normally-open switch 52 is intended to indicatesuch an auxiliary foot-control circuit. When switch 52 is closed, as bythe foot of the 7 operator, solenoid 24 is actuated and ratchet 26 isadvanced 30, thus to tune in the station associated with the particularposition to which the rotary switch is now advanced. Upon release offoot pressure, switch 52 opens, and the indicating la'mp associated withthe station then tuned-in.

*asvasso 7 is illuminated, as will be readily understood from thedescription previously given hereinabove. Repeated operation offoot-switch 52 will bring in sequentially the stations associated withthe various positions of the rotary switch, and will illuminatesequently the individual lamps associated with the said stations. Wehave described a preferred embodiment of our invention. Variousmodifications will occur tothose skilled in the art.

Having described our invention. we claim: 1. In a radio apparatus, anannunciator system comprising: a source of supply voltage; a sequenceswitch actuated by a solenoid in response to a. current of at leastpredetermined magnitude; a plurality of selector circuits operativelyassoelated with said rotary switch; a plurality of manually-operatedswitches operatively asso- 'ciated with said selector circuits throughthe switch, for opening said low resistance path,

when said sequence switch has effected selection of the selector circuitassociated with said closed switch, to efiect cessation of actuation ofsaid sequence switch; and means, including said sequence switch, forclosing, substantially concurrently with said opening of said low resistance path, a high resistance path which includes, in series, said sourceof supply voltage,

said solenoid, the individual indicator means identified with saidselected selector circuit, and the other of said indicating means, saidother indicating means being connected in shunt with each other, theresistance of said high resistance path being such that the currentthrough said solenoid is smaller than said predetermined magnitude, thecurrent through the series-con- 1 nected indicating means identifiedwith said selected circuit is sufiicient to effect activation thereof,and the current through said other shunt-connected indicating meansisinsufilcient to efl'ect activation thereof.

2. In a radio receiver, an annunciator system comprising: a source ofsupply voltage; a rotary switch actuated by a solenoid in response to-acurrent or at least predetermined magnitude; a plurality of pre-tunedstation-selector circuits operatively associated with said rotaryswitch; a plurality of pushbutton switches operatively associated withsaid pre-tuned circuits through the agency of said rotary switch; aplurality of individual indicator lamps operatively associated with saidrotary switch, each of said lamps being identified with a differentcircuit of said .pre-tuned station-selectorcircuits; means, o'perativeupon closing of a pushbutton switch, for completing a low resistancepath, which includes said source of supply voltage and said solenoid butexcludes said indicator lamps, to effect current flow of at least saidpredetermined magnitude and to effect actuation of said rotary switch;means, including said rotary switch, for opening said low resistancepath, when said rotary switch has effected selection oi. the pretunedcircuit associated with said closed pushbutton switch, to

\ ei'fect cessation of actuation of said rotary switch; and means,including said rotary switch, for closing, substantially concurrentlywith said opening of said low resistance path, a high resistance pathwhich includes, in series, said source of supply voltage, said solenoid,the individual lamp identified with said selected pretuned circuit, andthe other of said lamps, said 10 other lamps being connected in shuntwith each identified with said selected pro-tuned circuit is sufiicientto effect incandescence thereof, and the current through saidothershunt-connected lamps' is insufiicient to eil'ect incandescencethereof.

3. In a radio apparatus; a plurality of keys,

each of said keys being identified with a difi'erent circuit; aplurality of individual indicator means associated with said keys;selector mechanism, operative in response to the actuation of a key,

for effecting automatically selection 01' a circuit;

means, operative upon said actuation of said key, for: connecting a lowresistance path in shunt with said plurality oi indicator means tomaintain said indicator means in inactive condition during operation ofsaid selector mechanism:

and means, automatically operative when the selection of the circuit hasbeen eflected, for opening said shunt path and for connecting theindividual indicator means identified with the cir- 5 cult selected inseries with the other of said in dicator means, said other indicatormeans being connected in shunt with each other, thus to activate the'indicator means identified with the station selected while maintainingsaid other in- 0 dicator means in inactive condition.

4. In a radio receiver; a plurality of pushbuttons, each of saidpushbuttons being identified with a difierent station; individualindicator lamps associated with said pushbuttons; station selectormechanism operative in response to the actuation 01' a pushbutton fortuning automatically said receiver to a selected station; meansoperative upon said actuation of said pushbutton for connecting a lowresistance path in shunt with'said indicator lamps to maintain saidindicator lamps extinguished during operation of said selectormechanism; and means automatically operative when the selection of thestation has been eflected, for opening said shunt path and forconnecting the individual indicator lamp identified with the stationselected in series with the other of said lamps, said other lamps beingconnected in shunt with each other, thus to illuminate the indicatorlamp identified with the station selected while maintaining said otherlamps in extinguished condition.

' OTTO C. KEIL, Ja.

JESSE HEWITT LOF'ION.

5 REFERENCES CITED The following referenices are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 1,777,796 Hubbell Oct. '7, 19302,241,156 Powell May 6, 1941 2,387,444 Hayslett Oct. 23, 1945 2,424,243Lowell July 2'7, 194'? Certificate of Correction Patent No. 2,472,536.June 7, 1949.

OTTO C. KEIL, JR., ET AL. It is hereby certified that errors appear inthe printed specification of the above numbered patent requiringcorrection as follows:

Column 1, line 30, for annunciation read anmmciator; column 2, line 31,for conductors 37-42 read conductors 37-44; column 5, line 13, beforethe word bypassed insert is; line 41, after one insert path; column 6,line 19, for Wipecontacts read wiper contacts; column 7, line 6, forsequently read sequentially; and that the said Letters Patent should beread with these corrections therein that the same may conform to therecord of the case in the Patent Ofiice.

Signed and sealed this 8th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents.

